Optical fiber transmission has advantages such as strong interference immunity, a low loss, and high transmission reliability. Therefore, fiber-optic communication has become a main transmission means on a modern communications network, and is applied to various fields in daily life. Generally, aspects such as optical fiber test, optical cable layout, and a fault check all involve optical fiber length measurement. It can be said that optical fiber length measurement is an important technical basis for implementing fiber-optic communication.
Currently, an optical fiber length is mostly measured by using an optical fiber length measurement instrument. For example, the optical fiber length is measured by using an optical time domain reflectometer (optical time domain reflectometer, OTDR), an optical frequency domain reflectometry (optical frequency domain reflectometry, OFDR), an optical coherence domain reflectometry (Optical Coherence Domain Reflectometry, OCDR), and the like. These measurement manners have many deficiencies such as a high measurement cost and poor measurement precision, and consequently, these measurement manners are limited to some degree in a practical application. Therefore, a new solution for measuring an optical fiber length is desperately needed currently.